Idk if they changed the level up thing or whatever but this is sort of like it x)
*READ WARNING AT BOTTOM*
You need 1 battle pet thats higher level than the rest of your pets.
Take that pet and put it in a cage,
Put the cage on your actionbar,
You can now spam click that button on the action bar and your character will shine golden like on a level-up.
Fun for all ages.
*WARNING* this happens because the pet is too high level for you tame out of the cage, so this means you cant get it back as a non combat pet unless you level another pet to be higher than the one you took out.
Note: Because you need 1 pet to be higher than the rest this can be hard if you have alot of 25 pets, idk if u can take em all out in a cage, or if that would be worth it to you.